Pharmacokinetic study of the oral fluorouracil antitumor agent S‐1 in patients with impaired renal function

Although dose reduction of S‐1 is recommended for patients with impaired renal function, dose modification for such patients has not been prospectively evaluated. The aim of the present study was to investigate the pharmacokinetic parameters of 5‐fluorouracil, 5‐chloro‐2,4 dihydroxypyridine and oteracil potassium, and to review the recommended dose modification of S‐1 in patients with renal impairment. We classified patients receiving S‐1 into 4 groups according to their renal function, as measured using the Japanese estimated glomerular filtration rate (eGFR) equation. The daily S‐1 dose was adjusted based on the patient's eGFR and body surface area. Blood samples were collected for pharmacokinetic analysis. A total of 33 patients were enrolled and classified into 4 groups as follows: 10 patients in cohort 1 (eGFR ≥ 80 mL/min/1.73 m²), 10 patients in cohort 2 (eGFR = 50‐79 mL/min/1.73 m²), 10 patients in cohort 3 (eGFR = 30‐49 mL/min/1.73 m²), and 3 patients in cohort 4 (eGFR < 30 mL/min/1.73 m²). Those in cohorts 3 and 4 treated with an adjusted dose of S‐1 showed a similar area under the curve for 5‐fluorouracil (941.9 ± 275.6 and 1043.5 ± 224.8 ng/mL, respectively) compared with cohort 2 (1034.9 ± 414.3 ng/mL). Notably, while there was a statistically significant difference between cohort 1 (689.6 ± 208.8 ng/mL) and 2 (P = 0.0474) treated with an equal dose of S‐1, there was no significant difference observed in the toxicity profiles of the cohorts. In conclusion, dose adjustment of S‐1 in patients with impaired renal function using eGFR is appropriate and safe.     

Classification of antipsychotic drugs by gene expression in the frontal cortex of mice.

Antipsychotic drugs are classified as typical and atypical based on extrapyramidal effects. However, since the frontal cortex is one of the most important regions for antipsychotic actions, this study attempted to classify antipsychotic drugs based on gene expression in the frontal cortex. Chlorpromazine and thioridazine were selected as typical antipsychotics, and olanzapine and quetiapine as atypical antipsychotics. Since these drugs have similar chemical structures, the effect of the basic structure on gene expression can be eliminated. Cluster analysis of microarray experiments separated 4-drug-administered mice into chlorpromazine-quetiapine and thioridazine-olanzapine groups. This classification scheme is different from that which is based on criteria currently used to group the typical and atypical drugs and suggests that antipsychotic drugs can be further separated into multiple groups.     

Induced tolerance to ischemia in gerbil hippocampal neurons

Brief ischemia induced tolerance to subsequent ischemia in the hippocampal neurons. Male Mongolian gerbils were subjected to 2 min of ischemia in an awake condition. This ischemic insult only rarely produced neuronal damage in the gerbil brain. One day (n = 9), 2 days (n = 9), or 4 days (n = 10) following the first brief ischemia, the animals (double-ischemia group) were subjected to the second ischemia for 5 min. The single-ischemia group received a sham procedure instead of the first ischemia and was identically subjected to the second ischemia 1 day (n = 9), 2 days (n = 10), and 4 days (n = 13) following the sham procedure. One week following the second ischemia, all gerbils were perfusion fixed and the neuronal density in the hippocampal CA1 sector was measured. In double-ischemia groups, the neuronal density per 1-mm length of the pyramidal cell layer was 103.4 +/- 93.1 (SD) in the 1-day subgroup, 125.6 +/- 64.2 in the 2-day subgroup, and 176.2 +/- 93.7 in the 4-day subgroup, while the density in normal gerbils was 254.7 +/- 18.6. The average neuronal density in the single-ischemia group was much lower than that in the double-ischemia group (whole control group: 10.9 +/- 27.4). Immunostaining using monoclonal antibody raised against 70-kDa heat-shock protein revealed an increase in 70-kDa heat-shock protein in the CA1 area following 2 min of ischemia. Very brief ischemia induces heat-shock proteins and, presumably, thereby renders neurons more tolerant to subsequent metabolic stress.     

Hepatic conversion of 1-(tetrahydro-2-furanyl)-5-fluorouracil into 5-fluorouracil in patients with hepatocellular carcinoma

The pharmacokinetics of 1-(tetrahydro-2-furanyl)-5-fluorouracil (FT) and its conversion into 5-fluorouracil (FUra) in liver tissue were studied in ten patients with hepatocellular carcinoma (HCC). The plasma concentration of FT after its intravenous injection (dosage: 800 mg) was computerfitted to a bi-exponential function (C = Ae-alpha t + Be-beta t), indicating a two-compartment disposition. The pharmacokinetic parameters did not significantly differ between the five patients with, and the five without cirrhosis of the liver. The plasma concentrations of FUra likewise showed no significant difference between the two groups. The rates of FT degradation in the liver tissue homogenate were similar for four of the patients with cirrhosis (0.10 +/- 0.05 mumol/g liver protein/30 min) and four of those without it (0.13 +/- 0.05). The rates of cytochrome P-450-dependent FUra formation in the microsomal fraction of liver tissue from two patients (1.1 and 1.3 nmol/mg microsomal protein/30 min) were dramatically reduced to less than half of those of two control subjects (2.4 and 2.7). The estimated rates of FUra formation in the soluble fraction (105,000 X g supernatant fraction) from the two patients (0.1 and 0.13 nmol/mg protein/30 min) were almost identical to those from the controls (0.12 and 0.14), suggesting that the rate in the soluble fraction from HCC patients may not be as strongly affected as the rate in the microsomal fraction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Iron deficiency down-regulates the Akt/TSC1-TSC2/mammalian Target of Rapamycin signaling pathway in rats and in COS-1 cells

Iron deficiency (ID) is one of the most commonly known forms of nutritional deficiencies. Low body iron is thought to induce neurologic defects but may also play a protective role against cancer development by cell growth arrest. Thus, ID may affect cellular pathways controlling cell growth and proliferation, the mechanism of which is still not fully understood. The serine/threonine protein kinase Akt and its downstream target, the mammalian Target of Rapamycin (mTOR), is known to play a crucial role in the regulation of cell growth and survival. Therefore, we hypothesized that Akt/mTOR pathway could be influenced by ID. Three-week-old male Wistar-strain rats were divided into 3 groups and the 2 groups had free access to a control diet (C group) or an iron-deficient diet (D group). The third group (PF group) were pair-fed the control diet to the mean intake of the D group. After 4 weeks, rats were killed and their brains were sampled. In separate experiments, COS-1 cells were cultured with or without the iron chelator deferoxamine. Western blots of brain samples and COS-1 lysates were used to analyze the expression and phosphorylation state of Akt, TSC2, mTOR, and S6 kinase proteins implicated in the Akt/mTOR pathway. Using 2 different ID models, we show for the first time that iron deficiency depresses Akt activity in rats and in COS-1 cells, leading to a decrease in mTOR activity.     

A primary lung carcinoma producing alpha-fetoprotein, carcinoembryonic antigen, and human chorionic gonadotropin. Immunohistochemical and biochemical studies

This article documents a patient with lung carcinoma that produced three oncofetal antigens including alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), and human chorionic gonadotropin (hCG). Serum AFP, CEA, and hCG-beta-subunit were extremely high--118,000 ng/ml, 133 ng/ml and 0.9 ng/ml, respectively. Immunohistochemical staining of these tumor markers revealed that these proteins were present in different cells. The pattern of lectin affinity electrophoresis of AFP resembled that of hepatocellular carcinoma. Also investigated was the reactivity of serum CEA to monoclonal antibodies against peptide or sugar moieties. Serum CEA values measured by antipeptide monoclonal antibodies were higher than those measured by antisugar monoclonal antibodies. The demonstration of AFP, CEA, and hCG in different tumor cells suggests that three genomes were not reactivated together in a cell, and the lung carcinoma probably consisted of at least three clones of cancer cells with different phenotypes.